Housing for a vacuum pump

ABSTRACT

Housing for a vacuum pump, in particular a NEG or IGP-NEG combination, comprising a body defining an interior space to accommodate the vacuum pump, wherein a first flange is connected to the housing comprising an opening to connect the vacuum pump to a vessel and a second flange connected to the housing to connect the housing to an additional vacuum pump at least during regeneration. Further, a movable shield element is used movable from a first position to a second position, wherein in the first position the opening of the first flange is unobstructed and in the second position the opening is blocked.

CROSS REFERENCE TO RELATED APPLICATION

This application is a Section 371 National Stage Application ofInternational Application No. PCT/IB2021/051079, filed Feb. 10, 2021,and published as WO 2021/161188 A1 on Aug. 19, 2021, the content ofwhich is hereby incorporated by reference in its entirety and whichclaims priority of British Application No. 2001783.6, filed Feb. 10,2020.

FIELD

The object of the present invention is a housing for a vacuum pump andin particular for a non-evaporable getter pump (NEG) or an ion getterpump (IGP)-NEG combination, a vacuum pump with such a housing and avacuum system with such a vacuum pump.

BACKGROUND

In numerous industrial and scientific instruments and systems anultrahigh vacuum is required with pressures below 10⁻⁷ mbar. For thegeneration of such a vacuum in a vacuum apparatus it is known to usecombinations of different pump types. Thus, a main pump or backing pumpis used to generate pressures from last to 10⁻¹ mbar to 10⁻³ mbar as lowvacuum. Usually, the main pump or backing pump is combined with anothervacuum pump to generate a high vacuum or even ultrahigh vacuum includingpressures below 10⁻⁷ mbar. Ultrahigh vacuum pumps encompass absorptionpumps in order to generate the desired pressures. This absorption pumpsencompass ion getter pumps (IGP) and volume getter pumps, i.e.evaporable getter material pumps (NEG). Both types of pumps comprise agetter material, wherein for example during operation of the NEGmolecules and gas particles from the vessel of the vacuum apparatus arebound to the surface of the NEG material and are thus do not participateanymore to the pressure inside the vacuum apparatus. Due to thisdeposition the active surface of the NEG material which contributes tothe pump performance of the NEG pump is reduced. If no active surface ofthe NEG is available anymore, the pump performance of the NEG tends tozero and the NEG pump must be regenerated. Regeneration of the gettermaterial is usually made by heating up the getter material. Therein, apart of the bound molecules and gas particles is set free during theregeneration process and must be removed from the vacuum apparatus by anadditional vacuum pump. In particular, during regeneration of the gettermaterial, the pressure inside the vessel of the vacuum apparatus may becontaminated by the molecules and gas particles set free from the gettermaterial. Consequently, the pressure increases which is not desirable.Therefore, it is well known to include a valve between the vacuum pumpand the vessel to separate the vacuum pump from the vessel of the vacuumapparatus during regeneration of the NEG material. However, due to thisvalve the distance between the vacuum pump and the vessel is increased,thereby reducing the conductance of the connection and thereby reducingthe pump performance of the vacuum pump since in the molecular flowregime the probability for a molecule or gas particle is to enter thevacuum pump is reduced for a low conductance.

SUMMARY

It is an object of the present invention to provide a housing for avacuum pump, improving the conductance of the vacuum pump and avoidingcontamination of the vacuum inside the vessel during regeneration of thevacuum pump.

A solution to the given program is provided by the housing according toclaim 1, the vacuum pump according to claim 6 and the vacuum systemaccording to claim 7.

The housing for a vacuum pump in accordance to the present invention inparticular for a NEG or an IGP comprises a body defining an interiorspace to accommodate the vacuum pump. In particular, the interior spacecontains the NEG material or the iron getter material of the NEG or IGP,respectively. Further, a first flange is connected to the housingcomprising an opening to connect the vacuum pump to a vessel. Thus,molecules or gas particles from the vessel can enter the interior spacethrough the opening and then interact with the vacuum pump in theinterior space. Further, the body comprises a second flange to connectthe housing to an additional vacuum pump at least during regeneration.Thus, the second flange might be connected to another vacuum pump onlyduring regeneration in order to pump the gas particles and molecules setfree during the regeneration process or alternatively the second flangeis used to connect the housing to a backing pump during operation.

In accordance with the present invention, a movable shielding element isused, wherein the shielding element is movable from a first position toa second position, wherein in the first position the opening of thefirst flange is unobstructed and in the second position the opening isblocked and preferably completely blocked. The shielding element isdisposed inside the interior space and in front of the opening of thefirst flange if in the second position. By the shielding element theconductance is reduced considerably between the vacuum pump and thevessel. Thus, during regeneration of the NEG, the shielding element ismoved into the second position. Molecules or gas particles set free fromthe vacuum pump during regeneration cannot re-enter the vessel andcontaminate the vacuum inside the vessel due to the low conductance. Itis more likely, and the probability is much higher that the gasparticles or molecules are pumped by the additional vacuum pumpconnected to the second flange.

Preferably, there is no valve arranged at the first flange preferablybetween the vacuum pump and the vessel or incorporated between the bodyand the flange. Due to the shielding element, the housing for the vacuumpump can be directly connected to the vessel in order to enhance andimprove the conductance during operation if the shielding element is inthe first position. No further element needs to be employed between thevacuum pump and the vessel.

Preferably, the shielding element is a sheet element that can be easilymanufactured, wherein the requirements to the shielding elements are lowsince no complete sealing is required by the shielding element.

Preferably, the shielding element is guided by a guiding track or guiderails to be movable from the first position to a second position.

Preferably, the shielding element comprises no sealing elastomer or thelike in order to provide a vacuum tight sealing. It is an object of thepresent invention that by the shielding element it is only necessary toreduce the conductance between the vacuum pump and the vessel to avoidcontamination of the vacuum in the vessel during regeneration of thevacuum pump since vacuum pump and vessel are in the molecular flowregime. Complete sealing between the interior space of the housing andthe vessel of the vacuum apparatus is neither necessary nor required.

Preferably, the shielding element comprises a magnetic element oralternatively the shielding element itself might be magnetic and madefrom a magnetic material. The magnetic element is connected with amagnetic handle outside the body of the housing in order to transfer themovement of the magnetic handle to the shielding element. Thus, by themagnetic handle the shielding element can be moved from the firstposition to the second position inside the interior space. It is notnecessary to provide any mechanical contact of feedthrough between thehandle outside the body and the shielding element that would cause aleakage and would require additional efforts for sealing the movableparts. Thus, due to the magnetic attraction between the magnetic handleand the magnetic element of the shielding element, the magneticshielding element itself can be moved in an easy way to control theposition of the shielding element.

Further, the present invention relates to a vacuum pump comprising anNEG and/or IGP vacuum pump in a housing as previously described.

Further, the present invention relates to a vacuum system comprising avacuum pump as previously described and a vacuum vessel, wherein thevessel is directly connected to the vacuum pump. In particular, no valveis disposed between the vacuum pump and the valve in order to enhancethe conductance between the vessel and the vacuum pump.

The summary is provided to introduce a selection of concepts in asimplified form that are further described in the detailed description.This summary is not intended to identify key features or essentialfeatures of the claimed subject matter, nor is it intended to be used asan aid in determining the scope of the claimed subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is perspective view of a housing in accordance with oneembodiment.

DETAILED DESCRIPTION

FIG. 1 shows the housing according to the present invention comprising abody 10 defining an interior space 12, wherein in the interior space 12the vacuum pump is disposed (not shown). Further, first flange 14 isconnected to the body 10, wherein to the first flange 14 a vacuumchamber or vessel can be connected. Further, the body comprises a secondflange 16 connected to the housing, wherein to the second flange 16another vacuum pump can be connected as backing pump or as vacuum pumpto pump the gas particles and molecules which are set free during theregeneration process of the vacuum pump inside the housing. Preferably,the vacuum pump inside the housing is an IGP or NEG.

Further, the housing comprises a shielding element 18 which is movablefrom a first position as shown in the figure to a second position infront of an opening 20 of the first flange 14. Therein, the shieldingelement 18 is guided by guiding tracks 22. If the shielding element 18is in the second position in front of the opening 20 of the first flange14, the direct way between the vessel connected to the first flange 14and the interior space 12 of the housing is obstructed. During theregeneration of the vacuum pump inside the housing, gas particles ormolecules set free from the vacuum pump are more likely leaving theinterior space 12 through an opening 24 of the second flange 16 thanthrough the opening 20 of the first flange 14. If the opening 20 of thefirst flange 14 is obstructed by the shielding element 18, the shieldingelement 18 reduces the conductance between the interior space 12 and thevessel connected to the first flange 14. Flow of the gas particles andmolecules inside the housing of the vacuum pump, the flanges 14, 16 andthe vessel is in the molecular flow regime. Thus, the shielding element18 is not necessarily completely sealing the interior space 12 from thehousing to the vacuum vessel. Instead, the shielding element justreduces the conductance between the interior space 12 and the vesselreasonably that it is more likely that the gas particles and moleculesleave the interior space 12 through the opening 24 of the second flange16 than returning to the vessel connected to the first flange 14contaminating the vacuum inside. Therefore, the shielding element, builtas shield metal element, neither comprises a sealing nor requires agap-free design to provide a leak tight configuration.

The shielding 18 is connected to a magnetic element 26 disposed withinthe interior space 12 of the housing. The magnetic element 26 isconnected to a magnetic handle 28 outside the housing and connected tothe magnetic element 26 by a magnetic force such that movement of themagnetic handle 28 is transferred to the magnetic element 26 and therebyto the shielding element 18. Thus, by moving the magnetic handle 28outside the housing, the shielding element 18 can be moved from thefirst position to the second position. No mechanical feedthrough isnecessary in order to move the shielding element 18. In particular, thebody of the housing is made from a non-magnetic material to allowmagnetic coupling of the magnetic handle 28 to the magnetic element 26.

By the present design of the housing, the vacuum pump inside theinterior space 12 of the housing can be placed in close proximity to thevacuum vessel connected to the first flange 14. No additional valveneeds to be placed between the first flange 14 and the vacuum vessel inorder to separate the interior space 12 from the vacuum vessel to avoidcontamination of the vacuum inside the vacuum vessel during regenerationof the vacuum pump. Thereby, the conductance is enhanced, enhancing thepump performance of the vacuum pump inside the housing.

Although elements have been shown or described as separate embodimentsabove, portions of each embodiment may be combined with all or part ofother embodiments described above.

Although the subject matter has been described in language specific tostructural features and/or methodological acts, it is to be understoodthat the subject matter defined in the appended claims is notnecessarily limited to the specific features or acts described above.Rather, the specific features and acts described above are described asexample forms of implementing the claims.

1. A housing for a vacuum pump, in particular a NEG or IGP-NEGcombination, comprising: a body defining an interior space toaccommodate the vacuum pump, a first flange connected to the body andcomprising an opening to connect the vacuum pump to a vessel, and asecond flange connected to the body to connect the housing to anadditional vacuum pump at least during regeneration, characterized by amovable shielding element disposed inside the interior space of the bodyand movable from a first position to a second position wherein in thefirst position the opening of the first flange is unobstructed and inthe second position the opening is blocked without completely sealingthe interior space from the vessel.
 2. The housing according to claim 1,characterized in that no vacuum valve is arranged at the first flange.3. The housing according to claim 1, characterized in that the shieldingelement comprises a magnetic element connected with a magnetic handleoutside the body to transfer the movement of the magnetic handle to theshielding element.
 4. The housing according to claim 1, characterized inthat the shielding element is a sheet metal element.
 5. The housingaccording to claim 1, characterized in the shielding element comprisesno sealing.
 6. A vacuum pump comprising a NEG element and/or an IGPelement and a housing in accordance with claim
 1. 7. A vacuum systemcomprising a vacuum pump according to claim 6 and a vacuum vesseldirectly connected to the vacuum pump.